Embodiments of the disclosure relate to a capacitor assembly. More particularly, embodiments of the disclosure relate to thermal management of the capacitor assembly and method of forming a capacitor assembly.
Capacitors, at times, need to be operated at increased voltage and current levels. For example, power capacitors are widely used in inverters, typically in a direct current (DC) link of an inverter. Typical rated voltage for such DC-link capacitors ranges from 270 Volts DC to 1100 Volts DC. Additionally, the capacitor is required to deliver current of tens to a few hundred of Amperes.
Therefore, often, a number of capacitors are assembled into a capacitor bank in order to distribute large amplitude of ripple current, or to achieve the desired capacitance. The capacitor bank along with a potting compound is typically encapsulated in a resin to prevent moisture ingress and then sealed in a closed housing, thereby forming a capacitor assembly. Typical potting compounds used in such a capacitor assembly have a thermal conductivity lower than 0.5 W/m-K. Use of such potting compounds severely affects heat transfer capability within the capacitor assembly. Moreover, under high ripple current condition, low thermal conductivity of the potting compound leads to capacitor self-heating. Self-heating of the capacitor typically results in thermal degradation of dielectric materials employed in the capacitor assembly and eventually the failure of the capacitor assembly.
In some instances, the capacitors of the capacitor assembly may be exposed to transient events. For example during starting operation, the capacitor needs to carry significantly higher ripple current compared to normal operating condition. Even though such starting operation does not last for more than a couple of minutes, if the capacitor assembly cannot dissipate heat quickly and effectively, chances of thermal runaway increases.
Therefore, there exists a need for an improved capacitor assembly and methods of forming such a capacitor assembly.